From US 2004/0073359 it is known to use a camera for picking up an image of a landmark 17 and acquire an image data of the landmark 17 affixed to the load rack. The described system of this document uses the land marks for position control of the forklift truck. However the prior art does not describe how to avoid bad position control. For example in the prior art systems the camera at the fork lift truck has to have high positioning precision, so that the camera can be used for exact positioning of the cargo using one landmark. The camera has to have high precision since the camera is used for positioning of the load using one landmark when the load e.g. should be lifted or moved. If the camera has low positioning performance there is a risk that the forklift truck is not positioned correctly when e.g. a load should be lifted. This may result in damage of the load or load rack when handling the load.
Yet another problem with prior art systems that uses landmarks is that they require that the camera at the forklift truck is exactly positioned at the forklift truck, so that the camera can be used for exact positioning of the cargo and the forks. If the camera is not positioned correctly on the forklift truck there is a risk that the forklift truck is not positioned correctly when e.g. a load should be deposited or picked-up. This may result in damage of the load or load rack when handling the load. Since the cameras on the prior art systems are sensitive to exact positioning, the prior art systems are also sensitive to shocks, since a shock may cause that the camera moves from its position.
There is therefore a need for an improved solution for determining a load position, which solution solves or at least mitigates at least one of the above mentioned problems, especially at automatic pallet handling.